Traditionally, personal cleansing was usually carried out using solid soap bars containing alkali metal salts of fatty acids (soaps) as a surfactant. Nowadays, personal cleansing is a daily activity in most countries, and cleansing compositions have to meet customer needs and preferences, such as being very mild, easy applicability, and sufficient lathering. Soap bars are not satisfactory in meeting these requirements, especially in terms of mildness.
Furthermore, in liquid formulations, soap-based systems require adding thickening agents such as highly salt-resistant polymeric components to produce viscosities preferred by consumers. This thickening approach can cause a composition to exhibit dramatic viscoelastic properties during use and impact other product performance attributes (e.g., lathering properties). Because of this, many personal cleansing compositions have been changed to surfactant formulations without soap ingredients. However, many of these formulations fail to provide a preferable rinse feel associated with the cleansed skin. As a result, such a formulation fails to provide a rinse feel similar to that provided by soap, which is desired by many customers, especially those in Asia.
The term “rinse feel” refers to the feeling of the skin when lather is rinsed from the skin following the application of a cleansing composition. The term “soap-like rinse feel” as used herein refers to a feeling similar to that provided by soap; a soap-like rinse feel is a “draggy” rinse feel generated by a friction between the hand and the skin during the rinsing process.
Several attempts have been made to provide cleansing compositions that, while exhibiting mildness, provide the soap-like rinse feel.
For example, Patent Document 1 describes a mild liquid skin cleansing composition with improved lathering and rinse feel, containing: an alkyl ethoxylated sulfate having an average degree of ethoxylation of at least 2.0; an amphoteric surfactant selected from betaine surfactants, imidazoline surfactants, aminoalkanoate surfactants, and iminodialkanoate surfactants; an N-acylamino acid surfactant or a salt thereof; a cationic cellulose ether derivative; 0.2 to 2.0 parts by weight of a C8-C20 fatty alcohol; and 0.1 to 5 parts by weight of a water-insoluble salt of a C14-C22 fatty acid. The viscosity of the composition is within the range of 5000 to 11,000 cps.
Patent Document 2 describes a mild personal cleansing composition containing: (a) 3 to 10 parts by weight of an alkyl ethoxylated sulfate having an average degree of ethoxylation of at least 2.0; (b) 3 to 10 parts by weight of an amphoteric surfactant selected from betaine surfactants, imidazoline surfactants, aminoalkanoate surfactants, and iminodialkanoate surfactants; (c) 0.1 to 3 parts by weight of an N-acylamino acid surfactant or a salt thereof; (d) 0.01 to 0.5 parts by weight of a cationic cellulose ether derivative; (e) 50 to 94 parts by weight of water; and (f) 0.2 to 2.0 parts by weight of a C8-C20 fatty alcohol. Also a method of producing a personal cleansing composition is described. It is stated that the composition is mild and lathers well with an improved rinse feel.
Patent Document 3 describes a cleansing composition providing a soap-like rinse feel. The composition contains a lathering surfactant system, specific polymers, and oil ingredients.
Patent Document 4 describes a rinse-off liquid personal cleansing composition containing surfactants and water, wherein the composition contains less than 8% by weight of a first surfactant selected from crystallizing anionic surfactants and contains greater than 3% by weight of a second surfactant selected from non-crystallizing anionic surfactants, amphoteric surfactants, nonionic surfactants, and zwitterionic surfactants.
Patent Document 5 describes a liquid personal cleansing composition containing water, about 1% to about 60% by weight of a water-soluble surfactant, and a water-insoluble oil selected from highly branched poly-α-olefins having a number average molecular weight of about 1000 to about 25,000.
Also, Patent Document 6 describes a liquid personal cleansing composition containing surfactants, water, and water-insoluble oils.
Further, Patent Document 7 describes a liquid personal cleansing composition containing water, surfactants, and 0.5% by weight or greater of water-insoluble oils, wherein the water-insoluble oils provide a mean change in friction meter reading for the composition of 2 or greater as measured by a friction meter technical test method.
As described above, the personal cleansing compositions described in Patent Documents 1 to 7 provide an improved rinse feel. It is stated that these compositions provide an excellent rinse feel, which is a “draggy” and “soap-like” rinse feel, and also are mild to the skin. However, the above compositions cannot be completely considered to provide a soap-like rinse feel, and also they have a different texture from that of soap.